Rod section of an earth drilling string

ABSTRACT

A rod section of a ground drilling rod, wherein the rod section is configured at its end as a plug connection and comprises at one end (a) a connection plug or (b) a connection socket, wherein the connection plug on the outside or the connection socket on the inside comprises nonround segments along a cross section, wherein the cross section is constant in configuration.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority pursuant to 35 U.S.C. 119(a)-(d) to German Patent Application No. DE 102018008533.4 filed Oct. 31, 2018, the entire contents of which are incorporated herein by reference for all purposes.

FIELD OF THE INVENTION

The invention relates to a rod section of a ground drilling rod, a driving element for driving a ground drilling rod into the ground, a rod section system and a ground drilling device.

BACKGROUND

During rod-based drilling in the ground, especially to produce so-called horizontal boreholes, which may run substantially parallel or at a relative slight angle of inclination to the ground surface, a drill head is advanced by means of a drilling rod by a drilling device situated on the ground surface or in a construction pit. The drill rods used in this case usually consist of individual rod sections which are joined together and which are mounted gradually on the rear end of the already drilled drilling rod and connected to it.

Various designs are known for connecting the rod sections together. Thus, the rod sections may be connected by means of a thread connection and/or a plug connection.

It is known from DE 10 2011 010 958 A1 how to provide a possibility for connecting two rod sections of a drilling rod which combines the benefits of the thread connections and the axial plug connections known in the prior art. This describes a plug connection which—similar to a thread connection—is based on spiral projections/grooves extending on a circular-shaped threaded plug or in a corresponding threaded socket, the projections/grooves being designed so that the characteristic self-locking of a threaded connection does not occur.

Starting from this prior art, the problem which the invention proposes to solve is to indicate an improved plug connection for a drilling rod, especially a rod section, which is in particular more simple in its construction.

SUMMARY

The invention is based on the idea of indicating a possibility of connecting two rod sections of a drilling rod and/or a rod section to a driving element and/or a further element of the drilling rod, based on nonround segments of a constant cross section.

The invention creates a rod section of a ground drilling rod, wherein the rod section is configured at its end to form a plug connection and comprises at one end (a) a connection plug or (b) a connection socket. The connection plug on the outside or the connection socket on the inside comprises nonround segments along a cross section. The cross section is constant in configuration.

The term “rod section” in the sense of the invention comprises an element extending along a longitudinal axis, which may be part of a ground drilling rod or a drill string for the soil. The rod section may be configured as an element with an assigned function (transmitter housing, drilling tool, or the like) arranged at the front in the drill string or as an element merely lengthening the drill string as a “normal” rod section. The rod section may comprise mechanical ducts, such as for drilling fluid, electrical cables, electrical elements and/or electronic elements. The rod section may have a special function in the ground drilling rod, for example, it may be designed as a transmitter housing.

A rod section may comprise a first end with a connection plug or a connection socket as described. The rod section moreover may comprise a second end, at a distance from the first end, which usually comprises the other element of the pair of the plug connection. The rod section, moreover, may have a center line extending from the first end to the second end. The cross section of the connection plug or the connection socket may for example be a cross section perpendicular to the center line of the rod section.

The rod section in the sense of the specification may also be in particular a dual-tube rod section, in which both a so-called inner rod and a so-called outer rod are present. In such a dual-tube rod assembly, a drill head may additionally be driven in rotation via the inner rod from a driving device situated on the ground surface or in a construction pit, which also ensures the advancement of the drill head. The inner rod may be mounted for this purpose rotatably inside the outer rod of the dual-tube rod. The outer rod in a dual-tube rod assembly must either not rotate at all or only rotate with a slight speed. The rotations of the outer rod and the inner rod may occur interpedently of each other. A dual-tube rod assembly is especially suited to a rock drilling device, where the wear on the drill string is kept within bounds, since the outer rod coming into contact with the rock wall of the borehole can be advanced with no rotation or only slight speed along the rock wall of the borehole, while the inner rod driven at higher speed can be mounted in the outer rod, reducing the wear. The design of nonround segments may be provided in particular for the connection of the inner rod sections. Nonround segments may also be provided for the connection of the outer rod sections, but it is also possible to select a different kind of connection for the outer rod sections.

The term “ground drilling tool” encompasses a drill head arranged at the front end of the ground drilling rod or drill string, in which moving parts may be provided, but it may also be provided that the ground drilling tool comprises a nonmoving or rigid or largely nonmoving or rigid outer contour.

The term “ground drilling device” encompasses in the sense of the invention any device which moves in particular a rod consisting of rod sections in an existing or yet to be created passage in the ground, in order to create or expand a borehole, especially a horizontal drilling, or to lay pipelines or other long bodies in the ground. A ground drilling device may comprise a driving device which pushes and/or pulls a ground drilling rod. In addition or alternatively, it may be provided that the driving device drives the drilling rod in rotation.

The term “horizontal drilling” in the sense of the present specification encompasses in particular any kind of existing or yet to be created passages, preferably horizontal, in a body, especially ground passages including earth boreholes, rock boreholes, or earth conduits, as well as underground or aboveground pipelines and water canals which can be produced or pulled in by using a corresponding ground drilling device.

The terms “connection plug” and “connection socket” encompass in the sense of the specification a configuration as one element of a pair of mechanical coupling elements, of which the one (“connection plug”) can be introduced at least partly into the other (“connection socket”) in order to form the connection.

The term “nonround segment” encompasses in the sense of the specification a line segment along a cross section with which three different points along the cross section are joined together, wherein three points in particular cannot be situated along a straight line or a circle segment. The nonround segment may in particular be arc-shaped, including a configuration as an arbitrarily curved line outside of a circular arc segment. The nonround segment may be a curved line whose points have a different distance from any given point in space, especially a center point. The nonround segment may be described in partial regions by means of formulas of the kind

x(a)=[R _(m) −e·cos(3·α)]·cos(α)−3·e·sin(3·α)·sin(α)

y(a)=[R _(m) −e·cos(3·α)]·sin(α)+3·e·sin(3·α)·sin(α)

The nonround segments comprise lines, edges or sides which complement each other so as to form a closed polygonal line as a cross section. In particular, a nonround cross section can be formed which deviates periodically from a circle.

The term “constant” encompasses in the sense of the specification a quality of the cross section such that the cross section basically has no abrupt changes, i.e., the change in the function values describing the cross section can be limited arbitrarily by confining them to sufficiently small changes in the argument, such as the polar angle. The term “constant” refers to a macroscopic consideration, in which slight inconstancies might be present.

According to the invention, it has been found that a form fitting connection can be formed which may have mechanical benefits, for example, a small form factor. A connection can be created by which the highest torque in regard to the particular diameter can be transmitted. The connection can basically be designed with little or no notch effect. It is possible for the two rod sections being joined to have two-dimensional contact with each other, so that significantly less surface pressure may occur.

It has been found according to the invention that a cross section having nonround segments for the connection plug and connection socket may result in a greater torque transmitting capacity, without enlarging the diameter of the rod section or the participating connection plug and/or connection socket. In particular, nonround segments can be used which together comprise one or more segments obeying the same formula. In particular, the cross section resulting from the nonround segments can be a so-called polygon profile. According to the invention, it has been found that a polygon profile may also have deviations, yet nonetheless accomplish the effect according to the invention of reducing the surface pressure, so that very slight deviations from a polygon profile are possible. Deviations may be formed by circular segments and/or straight segments. The nonround segments may be respectively optimized in terms of a two-dimensional contacting of connection plug and connection socket.

In one preferred embodiment, various nonround segments are formed, so that in particular in the case of the connection socket partial regions or segments can be formed which may be different from each other and/or different from the contour of the connection plug. In this way, the connection plug may be easily introduced into the connection socket and a line contact between connection plug and connection socket is avoided, which would entail a high surface pressure. In particular, the connection socket may comprise not only a pure “enlargement” of the outer contour of the connection plug, but also in particular not be axially symmetrical and/or rotationally symmetrical to the center point. In particular, two mutually different nonround segments may be provided as the cross section of the connection socket and/or the connection plug.

In one preferred embodiment, two mutually different segments may alternate along the circumference, so that segments are formed which obey a given or predetermined function or formula, and which are separated by other segments which obey a different predetermined function or formula. Besides the providing of two segments, it is also possible to provide further segments. The providing of further segments is not ruled out, since according to the embodiment at least one further segment is formed, not represented by means of the (first) function, between two segments which can be represented by means of the (first) function. The segment which cannot be represented by means of the first function may be directly or indirectly adjacent to one of the two other segments. The segment which cannot be represented by means of the first function may consist of circular segments or straight segments.

In one preferred embodiment, in order to enlarge the two-dimensional contact area, it is provided that the nonround segments extend for a length of 20 mm to 120 mm, especially 30 mm to 110 mm, especially preferably 60 mm to 100 mm, in the longitudinal extension of the rod section.

In one preferred embodiment, an insertion segment is formed at the entrance side to the nonround segments, being configured at the end in particular on the connection plug or on the connection socket. The insertion segment may at first have the respective other element of the pair of the plug connection pass through it, in order to arrive in the region with the nonround segments. In this way, it is possible to achieve an easier introducing of the connection plug into the connection socket. In the insertion segment a relative rotational movement is possible between the connection socket and the connection plug.

In one preferred embodiment, inside the rod section there is present a plug connection for an electrical connection configured coaxially to the connection socket or connection plug. The configuration of the plug connection according to the invention makes it possible to close the electrical plug connection under constraint when forming the mechanical connection. The electrical connection can also be closed with no movement other than that to form the plug connection.

The invention also creates a driving element for driving a ground drilling rod into the ground. The driving element is configured to engage with a rod section. The driving element engaging with the rod section is configured (a) as a connection plug, having on the outside a cross section with nonround segments or (b) as a connection socket, having on the inside a cross section with nonround segments, while the cross section is constant.

In this way, a driving element of a driving device can be used, which is designed for the special geometry of the rod sections, so that a high torque can be transmitted in regard to the diameter. A two-dimensional contacting of the driving element with the rod section can be achieved and thus a significantly reduced surface pressure.

The term “driving element” in the sense of the specification encompasses an element of a driving device which provides for the advancement of the ground drilling rod in the soil, whereby the driving may be by pulling or by pushing, and the driving device in addition may be designed to drive the ground drilling rod in rotation. The driving element may be an element arranged on a carriage. The carriage may be moved back and forth in or on a frame, especially in parallel with the direction of the earth borehole being made.

In one preferred embodiment, various nonround segments are present. In particular, nonround segments which can be described by means of the same function may be provided between segments which can be described by means of another function. In this way, it is possible to configure the connection socket in particular not just as a pure “enlargement” of the outer contour of the connection plug, but also in particular one that is configured not axially symmetrical and/or rotationally symmetrical to the center point. In particular, two mutually different nonround segments of the cross section of the connection socket and/or the connection plug can be provided.

In one preferred embodiment, the mutually different nonround segments alternate along the circumference, so that an easily constructed and easily manipulated cross section can be formed.

In one preferred embodiment, the nonround segments extend for a length of 20 mm to 120 mm in the longitudinal extension of the driving element.

In one preferred embodiment, an insertion segment is formed at the entrance to the nonround segments in order to make it easier to connect the driving element and the rod section. The driving element can be moved relatively to the rod section or the rod section relatively to the driving element for a certain region in the insertion segment.

In one preferred embodiment, a plug connection for an electrical connection to a rod section is present on the inside of the driving element. In this way, an electrical connection of the drill string can be accomplished by means of the driving element. An electrical connection need not be laid outside of the rod sections in order to provide a connection.

In one preferred embodiment, the plug connection is oriented coaxially to the connection socket or to the connection plug, so that a simple configuration can be achieved. A plug connection oriented coaxially to the connection socket or the connection plug may be rotation-invariant, especially when the connection socket and connection plug are formed substantially centered in regard to the cross section of the rod section or driving element. The design of the connection socket/connection plug with a plug connection is simplified. Furthermore, the plug connection can be formed on the element provided for the mechanical connection.

The invention also creates a rod section system, which comprises two or more rod sections of the above described configuration.

In one preferred embodiment, the connection socket has a form different from the connection plug. In particular, the connection socket may be configured not only as a pure “enlargement” of the outer contour of the connection plug, but also in particular not axially symmetrical and/or not rotationally symmetrical to the center point. For example, partial regions of the cross section may serve as nonround segments for a clockwise rotation as a bearing surface for corresponding bearing surfaces of the connection plug and partial regions may serve as nonround segments for a counterclockwise rotation as a bearing surface for corresponding bearing surfaces of the connection plug.

Moreover, the invention relates to a ground drilling device which comprises a driving element of the above described configuration.

The preceding remarks, as well as the following description of an exemplary embodiment, do not constitute any renouncing of particular embodiments or features.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention shall be explained more closely below with the aid of an exemplary embodiment represented in the drawings.

The drawings show:

FIG. 1, an isometric view of a connection plug;

FIG. 2, a side view of the connection plug of FIG. 1;

FIG. 3, a view of the connection plug of FIG. 1 from the front;

FIG. 4, an isometric view of a connection socket;

FIG. 5, a view of the connection socket of FIG. 4 from the front, and

FIG. 6, a cross section transverse to the longitudinal direction in the region of a connection plug inserted into a connection socket.

DETAILED DESCRIPTION

FIG. 1 shows schematically in an isometric view a connection plug 1, as may be provided at the end of a rod section or a driving element. The end of the rod section or the driving element is configured to form a plug connection. The connection plug 1 is part of a pair which is formed in addition by a connection socket 2, as is described more closely below. From the depicted first end of the rod section or driving element there extends a center line 3 to a second end (not shown) of the rod section or driving element. The connection plug 1 comprises nonround segments 4 on its outside along a cross section 5. The nonround segments 4 extend in the longitudinal direction along the center line 3 for a region of 85 mm. There is formed a cross section 5 situated perpendicular to the center line 3 and comprising substantially three nonround segments 4.

FIG. 2 shows schematically the connection plug 1 from the side, wherein insertion segments 6 are formed on the connection plug 1, being situated adjacent to the end of the rod section or the driving element, in order to allow an easier connection to a connection socket 2. Depressions are formed, extending in the longitudinal direction (along the center line 3), being provided for each nonround segment 4. The depressions of the insertion segment 6 can interact as an insertion aid with a correspondingly shaped insertion segment 6 on the connection socket 2 in order to allow an orienting between connection plug 1 and connection socket 2.

From FIG. 3 it is seen that the rod section or the driving element also comprises an electrical contact, which is present in the form of an (electrical) connection plug 7, formed coaxially to the (mechanical) connection plug 1.

FIG. 4 shows in an isometric representation a connection socket 2, which may be present at one end of a rod section or a driving element. The connection socket 2 comprises an insertion segment 6, which extends across a longitudinally axial region of 20 mm.

FIG. 5 shows a front view of the connection socket 2. Nonround segments 8 are provided to form an inside cross section 9 of the connection socket 2. The connection socket 2 comprises coaxially an electrical connection socket 11 for an electrical connection.

FIG. 6 shows a cross sectional representation which is produced by introducing the connection plug 1 into the connection socket 2. The sectioning is done substantially perpendicular to the center line 3. FIG. 6 shows that the connection socket 2 in the exemplary embodiment shown is not only a mere enlargement of the outer contour of the connection plug 1, but also contains other nonround segments 10 which the connection plug 1 does not contain. Whereas for the connection plug 1 there are substantially provided three nonround segments 4, the connection socket 2 contains two times three nonround segments 8, 10, of which three correspond to the three segments of the connection plug 1, but these are not formed across the entire region, as in the connection plug 1. The three nonround segments 8 corresponding to the nonround segments 4 of the connection plug 1 are separated by three of the nonround segments 10 different from the nonround segments 4. This is shown schematically in FIG. 6 in that the nonround segments 8 which resemble each other in regard to the connection plug 1 and connection socket 2 are provided with a dashed region, and the regions in which the nonround segments 10 are not similar are marked by a dashed and dotted region. 

1. A rod section of a ground drilling rod, wherein the rod section is configured at its end as a plug connection and comprises at one end: (a) a connection plug or (b) a connection socket, wherein the connection plug on an outer surface thereof, or the connection socket on an inner surface thereof, comprises nonround segments along a cross section, wherein the cross section is constant in configuration.
 2. The rod section according to claim 1, wherein various nonround segments are formed.
 3. The rod section according to claim 2, wherein the various nonround segments alternate along the circumference.
 4. The rod section according to claim 1, wherein the nonround segments extend for a length of 20 mm to 120 mm in the longitudinal extension of the rod section.
 5. The rod section according to claim 1, wherein an insertion segment is formed at the entrance side to the nonround segments.
 6. The rod section according to claim 1, wherein inside the rod section there is present a plug connection for an electrical connection configured coaxially to the connection socket or connection plug.
 7. A driving element for driving a ground drilling rod into the ground, being configured to engage with a rod section, wherein the driving element engaging with the rod section is configured: (a) as a connection plug, having on the outside a cross section with nonround segment; or (b) as a connection socket, having on the inside a cross section with nonround segments, while the cross section is constant.
 8. The driving element according to claim 7, wherein various nonround segments are formed.
 9. The driving element according to claim 8, wherein the segments alternate along the circumference.
 10. The driving element according to claim 7, wherein the nonround segments extend for a length of 20 mm to 80 mm in the longitudinal extension of the driving element.
 11. The driving element according to claim 7, wherein an insertion segment is formed at the entrance side to the nonround segments.
 12. The driving element according to claim 7, wherein inside the driving element there is present a plug connection in the form of an electrical connection plug or an electrical connection socket for an electrical connection.
 13. The driving element according to claim 12, wherein the plug connection is oriented coaxially to the connection socket or the connection plug.
 14. A rod section system comprising two or more rod sections according to claim
 1. 15. A ground drilling device comprising a driving element according to claim
 7. 